1. Field of the Invention
This invention relates to a floppy disk drive which comprises a magnetic head required for recording information on and/or reproducing information from a floppy disk, a carriage for carrying the magnetic head, and drive means for driving the carriage so as to enable the magnetic head to scan a track formed on a side of the floppy disk.
2. Description of the Prior Art
Head supporting members, such as a head carriage 1 and a head support arm 2 shown in FIG. 4, have been made of synthetic resin so far. According to FIG. 4, the proximal end 2a of the head support arm 2 is secured to an arm supporting block 3, which is formed integrally with the proximal end of the head carriage 1, through a hinge plate 4 with screws 5. A pair of upper and lower gimbal plates 6 made of leaf spring are welded to the respective free ends 1b and 2b of the head carriage 1 and the head support arm 2 on the peripheries 6a thereof so as to face each other, and thereby, a pair of upper and lower magnetic heads 7 which are stuck on the respective centers 6b of the gimbal plates 6 are resiliently supported by the gimbal plates 6.
Moreover, a pair of upper and lower shielding rings 8 are stuck on the respective gimbal plates 6 so as to surround the magnetic heads 7, and shield covers 9 are stuck on the respective other sides of the free ends 1b and 2b of the head carriage 1 and the head support arm 2, which are opposite to the sides to which the respective gimbal plates 6 are secured. Each gimbal plate 6 is supported by a pin 10, which projects from each free end 1b, 2b of the head carriage 1 and the head support arm 2, at the center thereof and on the other side opposite to the side to which the magnetic head 7 is secured.
A pair of flexible printed-circuits 11 are arranged respectively along the head carriage 1 and the head support arm 2 so as to face each other, and each end 11a of the printed circuits 11 and a plurality of terminals 12 which project from the magnetic heads 7 are soldered together. Further, intermediate portions 11b of the printed circuits 11 are welded to the head carriage 1 and the head support arm 2, respectively, through projections 13 projecting therefrom.
When put into action, a pair of magnetic heads 7 are brought into elastic contact with the respective sides of a floppy disk 14, which is one example of a disk-like recording medium, and mounted on a floppy disk drive, and while the head carriage 1 is discretely moved together with the head support arm 2 in the radial direction of the floppy disk 14, information is recorded on or reproduced from the rotating floppy disk 14 selectively through one of the magnetic heads 7. At that time, the shielding ring 8 and the shield cover 9 prevent the magnetic heads 7 from being influenced by an external magnetic field.
In the meanwhile, the shielding ring 8 made of magnetic material is small in size as shown in FIGS. 5A and 5B, and must be stuck on the gimbal plate 6 in accordance with a predetermined direction. In an actual process, after the magnetic head 7 is stuck on the center 6b of the gimbal plate 6, the periphery of the magnetic head 7 is coated with a synthetic resin 20 (FIG. 5B) to reinforce adhesion of the magnetic head 7, and before the synthetic resin 20 is cured, the shielding ring 8 is immersed in the synthetic resin 20 to adhere to the gimbal plate 6. Therefore, it is required to perform the sticking operation of the shielding ring 8 in a short period of time and with high accuracy to surround the magnetic head 7. The periphery 6a of the gimbal plate 6 is, thereafter, welded to the head carriage 1 or the head support arm 2.
Thus, there are some perplexing problems that the shielding ring 8 made of magnetic material is expensive; that the ring 8 is a separate part from the head carriage 1 and the head support arm 2, so that the assembling cost entailed; is too high, that it is very troublesome to stick the small ring 8 on the gimbal plate 6 so as to be in an accurate position and in accordance with the predetermined direction; and that the process of attaching the gimbal plate 6, on which the magnetic head 7 and the shielding ring 8 have been already stuck as described above, to the head carriage 1 or the head support arm 2 results in increasing the number of parts and the steps required for assembly, and raising the manufacturing cost.
Secondly, the head carriage 1 and the head support arm 2 are driven by a stepping motor (not shown) generally in such a way that, as shown in FIG. 6, one end of a needle bar 16 made of steel wire, or the like is put on a bracket which is integrally formed with the head carriage 1, and fixed to the bracket 15 by means of laying a plate 17 over the end of the needle bar 16, and fastening the plate 17 with screws 18 tightly to the bracket 15, and the other end of the needle bar 16 is engaged with the groove 19a of a feed screw 19 which is driven by the stepping motor. As a result, the head carriage 1 and the head support arm 2 are discretely moved in the radial direction of the floppy disk 14 due to the torque of the stepping motor.
Thus, there are other perplexing problems that the needle bar 16 is a separate part from the head carriage 1, so that the number of parts and the steps required for assembly are increased, and thereby, the manufacturing cost is raised; and that the screws 18 to fasten the plate 17 are apt to be loosened by vibrations, or the like, and results in imparting lost motions to the needle bar 16, or having the needle bar 16 fall from the bracket 15, so that the reliability of the floppy disk drive is lowered.